Figure 6. Maternal age-associated oocyte spindle and chromosome abnormalities suppressed by Nrf2 overexpression. (A) PBS (control group) or Nrf2 plasmid (overexpression group) was microinjected into old GV oocytes, which were arrested for 20 h with milrinone to allow synthesis of new Nrf2 protein. Results indicated that Nrf2 protein was efﬁciently overexpressed. (B) Representative examples of meiotic spindle and chromosomes at MII stage in young oocytes, old oocytes and old oocytes injected with PBS or Nrf2 plasmid. Arrowheads indicate misaligned chromosomes. (C) Incidence of spindle/chromosome defects in indicated oocytes. Data are expressed as the mean ± SD percentage from 3 independent experiments in which 100 oocytes were analyzed, *P<0.05 vs. control.